Fluke CableAnalyzer DSP-4000 Series, User Manual

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Basic Cable Testing
Troubleshooting Basics
7
7-27
Troubleshooting Basics
Troubleshooting LAN cable installations is most often required during cable
installation or modification. When cable is handled carefully and installed
correctly, it usually operates trouble-free for years.
Finding Cable Faults
A general rule for finding cable faults is as follows: With very few exceptions,
faults occur at cable connections. Cable connections include telecommunication
outlets, patch panels, punchdown blocks, and transition connectors.
Connections are the most likely places for faults for at least three reasons: (1)
Connections always alter the impedance of the transmission path, (2) connections
are likely places for faults caused by wiring errors and faulty or incompatible
hardware installation, and (3) connections always cause some crosstalk due to the
untwisting of cable pairs.
When cable is handled carelessly, faults can occur in the middle of the cable.
These faults can happen when the cable is stepped on, sharply bent, pinched by
cable ties or other hardware, or otherwise stressed.
A general procedure for finding cable faults (excluding sources of noise and traffic
faults) involves the following steps:
1. Run an Autotest on the cable.
2. If the Autotest fails, press
F
for specific information on the fault.
3. Inspect the cable for the suggested fault at the location indicated by the
diagnostics display.
4. Repair any faults you find. To quickly check your repair, run the test that
failed as a Single Test.
5. Run the Autotest again to verify the cable’s performance.
Table 7-1 on the next four pages shows examples of test tool displays for some
typical cable faults.